The invention relates to a weight-filling machine for containers, meaning a machine in which the end of the filling of the container is determined based on the change in said container""s weight in order to obtain a predetermined quantity of product inside the latter.
The invention relates more specifically to a weight-filling machine of the type in which a container to be filled is carried by a gripping device that is supported by a force sensor, and of the type in which the force sensor consists of a deformable component with a base end linked to a frame and an interface end on which is attached the gripping device.
Such a machine is for example described in the document of patent FR-A-2.770.292.
In this type of machine a gripping device carries the container. Said device can be tongs that are able to grab the container by the neck, as in the above-mentioned document, or a seat on which the container is placed. In both cases, the gripping device usually comprises additional means that guide the body of the container in order to guarantee its precise positioning.
Of course, the container gripping device must be supported by the force sensor in order for the latter to be entirely subjected to the weight of the container without there being any interference with other components of the machine.
Also, all forces sustained by the gripping device are fully retransmitted to the sensor.
However, the container transfer means that make it possible to bring the empty container to the gripper device and remove it once it is filled can malfunction. Said malfunctions can then be translated by the fact that significant forces are exerted on the gripping device and therefore on the sensor. Yet, it is provided that the force sensor be able to sustain forces relative to the weight of the containers it measures. Beyond that, it can sustain irreversible deformations that make it unusable and could even make it break.
Therefore, the object of the invention is to propose a new weight-filling machine design that makes it possible to effectively protect the sensor without changing in any way the precision with which it measures.
With this end in view, the invention proposes a machine of the type described previously, characterized in that the gripping device is linked to the interface end Using elastic means that urge the gripping device towards a normal position in which it rests on a support surface linked to the interface end, and in that the gripping device is mobile relative to the interface end along a protective direction, countering the elastic means, up to a stop position in which it comes in contact with a stop surface linked to the frame.
Based on other characteristics of the invention:
the gripping device is mounted on the interface end so as to be able to slide in relation to the interface end along a protection direction between its normal position and its stop position;
the protection direction is more or less horizontal;
the gripping device extends from the interface end along the protection direction in such a way that the container is out of plumb relative to the sensor;
the gripping device is mounted so that it slides on a cylindrical guide bar that is integral with the sensor""s interface end;
rotary blocking means are provided for the gripping device in relation to the sensor around the guide bar axis;
the weight sensor is a constant time sensor in the shape of a body that is equipped with at least one central lightening hole so that both ends are linked to each other by cross bars that are more or less parallel and whose junctions with the ends are deformable in order to form hinge points, and the cross bars are more or less parallel to the protection direction;
the gripping device and the frame delimit between them a tight compartment inside which the force sensor is set;
a flexible bellows that links the gripping device to the frame guarantees the tightness of the compartment.